1. Field of the Invention
This invention relates to a method for manufacturing a zinc wire, more particularly to a manufacturing method which can produce a highly ductile zinc wire.
2. Description of the Related Art
In general, zinc (Zn), which has a good anti-corrosion property, is largely used as a protective coating for metallic structures and is applied by means of a metal spraying process with the use of a spray gun. In addition, zinc may be sprayed on non-metallic materials so as to form a conductive outer layer on the non-metallic materials.
In order to facilitate carrying of the metal spraying apparatus, the zinc wires used when spraying a zinc layer onto the metallic structures and the non-metallic materials must be flexible so as to be formed into a coil. In use, the coiled zinc wire is connected to a spray gun so that it can be moved along with the gun and melted within the spray gun for spray-coating on the surfaces of the metallic structures and the non-metallic materials. Usually, the zinc wire used for spray-coating is made from zinc of more than 99.9% purity and has a diameter of about 1-6 mm. However, it is quite difficult to manufacture a 1-6 mm diameter zinc wire from a cast zinc ingot.
With the HCP (hexagonal close-packed lattice) crystalline structure, zinc is relatively hard and brittle at room temperature so that it has poor processability. Zinc becomes ductile at a higher temperature. At a temperature of 100.degree.-150.degree. C., the ductility of zinc substantially increases so that it can be pressed to form sheets or drawn into wires. When zinc is heated to a temperature of 200.degree. C., its grain size becomes coarse. Thus, zinc returns to its brittle form so that, when it undergoes manufacturing processes such as rolling or drawing, work-hardening occurs due to the deterioration of the zinc lattices.
As mentioned above, zinc is liable to become hard and brittle in the processing thereof. If the ductility of zinc is not increased enough to a proper condition during the manufacturing process, it would cause problems, such as wire jam, overload and wire breakage, to the machines used in the manufacturing processes, such as rolling and drawing. This will result in an increase in the manufacturing costs. In addition, if the final zinc wire product is hard and brittle, it cannot be wound into a coil and may even break.